α-Si_(1-x)C_x∶H薄膜材料的弹性反冲探测分析

介绍在中国原子能科学研究院HI 13串列加速器上,对α Si1-xCx∶H薄膜样品进行弹性反冲探测分析的方法和结果.用该加速器提供的高品质127I束流轰击α Si1-xCx∶H薄膜材料样品,用ΔE(gas) E(PSD)望远镜探测器,在前角区(30°角)测量从该样品中反冲的各元素的能谱.然后用离子束分析(IBA)程序SIMNRA对能谱进行拟合,得到样品中H,C和Si的比分及深度分布.     

表面高分辨弹性反冲探测分析

在中国原子能科学研究院 HI- 1 3串列加速器上建立了用 Q3D磁谱仪动量分析和ΔE- E粒子分辨对材料表面进行高分辨的弹性反冲探测分析技术 .用 1 0 0 Me V12 7I对 C/Li F多层样品的深度分布分析表明 ,表面分辨达到 1 .2 nm.所建立的ΔE(气体 ) - E(半导体 )望远镜探测器可同时分析从轻至中重的所有元素 .实测了新光电材料 Ga N,La2 Sr Cu O4 超导膜和新超硬材料 C3N4 (Si)等样品. High resolution depth profiling technique with elastic recoil detection analysis has been developed at the HI 13 tandem accelerator of CIAE. A depth resolution of 1.2 nm was achieved at the surface of the samples with the Q3D magnetic spectrometer and the focal plane detector. From light to medium heavy elements were simultaneous analyzed with a small Δ E E telescope. The method was applied to depth profile analysis of C/LiF multilayers, La 2SrCuO 4 superconductor and GaN foil samples.     

Crystal structure and ionic conductivity of Mg-doped apatite-type lanthanum silicates La10Si6-x Mgx O27-x（x=0–0.4）

Lanthanum silicates La10Si6-xMgxO27-x(x = 0–0.4) were prepared by solid state synthesis to investigate the effect of Mg doping on crystal structure and ionic conductivity. Rietveld analysis of the powder XRD patterns reveals that Mg substitution on Si site results in significant enlargement of channel triangles, favoring oxide-ion conduction. Furthermore,an increase of Mg concentration significantly influences the linear density of interstitial oxygen, which plays an important role in ionic conductivity. The Arrhenius plots of La10Si6-xMgxO27-x(x = 0–0.4) suggest that Mg-doped samples present higher conductivity and lower activation energy than non-doped La10Si6O27, and La10Si5.8Mg0.2O26.8exhibits the highest conductivity with a value of 3.0×10-2S ·cm-1at 700?C. Such conductive behavior agrees well with the refined results.The corresponding mechanism has been discussed in this paper.     

高分辨的弹性反冲探测分析技术

在中国原子能科学研究院HI－13串列加速器上建立了一套高分辨的弹性反冲探测分析技术,用高质量的127I重离子束轰击薄膜或块材靶样品,利用Q3D磁谱仪及其焦面探测器和纵向型双向型双电离室ΔE－E望远镜探测器两套探测系统,在前角区测量了靶中各种元素的反冲能谱,利用卢瑟福散射截离子在靶材料中的阻止本领,将能谱转换成元素的深度分布,利用Q3D磁谱仪系统,对C和H等轻元素的分析得到纳米级的深度分频谱,用ΔE－E望远镜探测器可同时得到靶材料上从轻至中重各种元素的深度分布,其深度分辨率达0－30nm。     

Comparison of Secondary Ion Emissions from Carbon Nanotubes under Bombardments of MeV Si and Si2 Clusters

The emission yields of H, H2, H3 and heavy ions from carbon nanotubes under bombardments of Si and Si2 clusters in an energy range of 0.3-3 MeV per atom are measured by using the time-of-flight technique (TOF). The emission yields of the secondary ions increase with increasing energy of Si and the electronic stopping processes play an important role. The enhanced emission yields of secondary ions induced by Si2 clusters at the low energies are clearly seen and attributed to the vicinage effect of the nuclear collision processes of cluster constituents and the secondary ion emissions are still dominated by electronic stopping processes at high energies.     

Electric properties and phase transition behavior in lead lanthanum zirconate stannate titanate ceramics with low zirconate content

The phase transitions, dielectric properties, and polarization versus electric field(P–E) hysteresis loops of Pb0.97La0.02(Zr0.42Sn0.58-x Ti x)O3(0.13≤ x ≤0.18)(PLZST) bulk ceramics were systematically investigated. This study exhibited a sequence of phase transitions by analyzing the change of the P–E hysteresis loops with increasing temperature.The antiferroelectric(AFE) to ferroelectric(FE) phase boundary of PLZST with the Zr content of 0.42 was found to locate at the Ti content between 0.14 and 0.15. This work is aimed to improve the ternary phase diagram of lanthanum-doped PZST with the Zr content of 0.42 and will be a good reference for seeking high energy storage density in the PLZST system with low-Zr content.     

加速器束流脉冲化及氢二次离子发射研究

详细介绍了快速高压晶体管开关在加速器束流脉冲化和用于二次离子测量的加速器飞行时间谱仪上的应用. 利用飞行时间法研究了碳纳米管在不同能量的Si和Si2团簇离子轰击下氢二次离子的发射. 实验结果表明， 在每个原子质量单位的速度为2.5×108 cm/s以上， Si和Si2离子引起的氢二次离子的发射主要受电子阻止过程控制； 在每个原子质量单位的速度为2.5×108 cm/s以下和Si2团簇离子轰击的情况下， 氢二次离子的发射产额明显增加， 团簇离子在靶表面的核能损增强效应起主要作用. The application of Fast High Voltage Transistor Switches (HTS) in pulsed ion beam and the time of flight(TOF ) setup is described. Secondary ion emissions from carbon nanotubes under bombardments of MeV Si and Si2 clusters are measured by using TOF. The measurements indicate that the yield of the secondary ion emissions of hydrogen increases with increasing energy of Si and it is attributed to the electronic processes. The yield of the secondary ions of hydrogen decreases with increasing energy of Si2 clusters and the enhancement of nuclear energy loss of cluster constituents at the surface of sample plays a more significant role in the secondary ion emission of hydrogen at the low energies.     

First-principles calculations on Si(220) located 6H–SiC(10■0)surface with different stacking sites

6H–SiC(10ˉ10) surface and Si(220)/6H–SiC(10ˉ10) interface with different stacking sites are investigated using first-principles calculations. Surface energies of 6H–SiC(10ˉ10)(case I, case II, and case III) are firstly studied and the surface calculation results show that case II and case III are more stable than case I. Then, the adhesion energies, fracture toughness values, interfacial energies, densities of states, and electronic structures of Si(220)/6H–SiC(10ˉ10) interfaces for three stacking models(AM, BM, and CM) are calculated. The CM model has the highest adhesion energy and the lowest interfacial energy, suggesting that the CM is stronger and more thermodynamically stable than AM and BM. Densities of states and the total charge densities give evidence that interfacial bonding is formed at the interface and that Si–Si and Si–C are induced due to the hybridization of C-2p and Si-3p. Moreover, the Si–C is much stronger than Si–Si at the interface,implying that the contribution of the interfacial bonding mainly comes from Si–C rather than Si–Si.     

Compression behavior and phase transition of β-Si_3N_4 under high pressure

The compressibility and pressure-induced phase transition of β-Si_3N_4 were investigated by using an angle dispersive x-ray diffraction technique in a diamond anvil cell at room temperature. Rietveld refinements of the x-ray powder diffraction data verified that the hexagonal structure(with space group P63/m, Z = 2 formulas per unit cell) β-Si_3N_4 remained stable under high pressure up to 37 GPa. Upon increasing pressure, β-Si3 N4 transformed to δ-Si_3N_4 at about 41 GPa. The initial β-Si_3N_4 was recovered as the pressure was released to ambient pressure, implying that the observed pressureinduced phase transformation was reversible. The pressure–volume data of β-Si_3N_4 was fitted by the third-order Birch–Murnaghan equation of state, which yielded a bulk modulus K_0= 273(2) GPa with its pressure derivative K_0= 4(fixed)and K0= 278(2) GPa with K 0= 5. Furthermore, the compressibility of the unit cell axes(a and c-axes) for the β-Si_3N_4 demonstrated an anisotropic property with increasing pressure.     

B和H离子顺次注入单晶Si 引起的缺陷及其热演变(英文)

室温下将130 keV,5x1014 cm-2 B离子和55 keV,1x1016 cm-2 H离子单独或顺次注入到单晶Si中,采用横截面试样透射电子显微镜(XTEM)和慢正电子湮没技术(SPAT) 研究了离子注入引起的微观缺陷的产生及其热演变。XTEM观测结果显示,B 和H 离子顺次注入到单晶Si 可有效减少(111) 取向的H板层缺陷,并促进了(100) 取向的H板层缺陷的择优生长。SPAT 观测结果显示,在顺次注入的样品中,B 离子平均射程处保留了大量的空位型缺陷。以上结果表明,B离子本身及B 离子注入所产生的空位型缺陷对板层缺陷的生长起到了促进作用。Abstract:Cz n-type Si (100) wafers were singly or sequentially implanted at room temperature with 130 keV B ions at a fluence of 5x1014 cm-2 and 55 keV H ions at a fluence of 1x1016 cm-2. The implantation-induced defects were investigated in detail by using cross-sectional transmission electron microscopy (XTEM) and slow positron annihilation technique (SPAT). XTEM results clearly show that sequential implantation of B and H ions into Si could eliminate the (111) platelets and promote growth of (100) platelets during annealing. SPATmeasurements demonstrate that in B and H sequentially implanted and annealed Si, more vacancy-type defects could remain in sample region around the range of B ions. These results indicat e that the promotion effect shouldbe attributed to the role of both B and B implanted induced vacancy-type defects.     

新型红色荧光粉NaLa_(0.7)(MoO_4)_(2-x)(WO_4)_x∶0.3Eu~(3+)的制备及发光性质研究

采用高温固相法合成具有余辉性能的发光材料NaLa_(0.7)(MoO_4)_(2-x)(WO_4)_x∶0.3Eu~(3+)(x=0,0.5,1,1.5,2)。用X射线衍射(XRD)和荧光光谱对样品的晶体结构和发光特性进行表征。测试结果表明,在900℃下烧结8 h所合成的NaLa_(0.7)(MoO_4)_(2-x)(WO_4)_x∶0.3Eu~(3+)样品为纯相Na La(Mo O_4)_2,样品可被近紫外光393nm和蓝光462 nm有效激发,其发射主峰位于615 nm处,属于Eu3+的5D0-7F2跃迁。Na La_(0.7)(Mo O_4)_(2-x)-(WO_4)_x∶0.3Eu~(3+)的发光强度随着W6+浓度的增加而增大,当W6+掺杂量x=1时发光最强,而后随W6+掺杂浓度的增加出现浓度猝灭现象。通过计算得到样品在393 nm和462 nm激发下的色坐标,当W6+的掺杂量x=1时,样品的红光色纯度最好。     

Enhancing exchange bias with diluted antiferromagnets

The exchange bias H(E) of coupled polycrystalline films of antiferromagnetic CoO and ferromagnetic Co was significantly enhanced by the systematic substitution of nonmagnetic Mg for Co in CoO. Samples in which either Co or Co(1-x)Mg(x)O were deposited first were investigated at temperatures from 10 to 300 K. With Co(1-x)Mg(x)O on the bottom, the increased interfacial uncompensated spin density of the single antiferromagnetic domain Co(1x)Mg(x)O crystallites produced the enhanced H(E). With Co on the bottom, a thin interfacial oxide layer was primarily responsible for the strongly increased H(E).     

Zn元素替代对MgGa2O4∶Cr3+的结构和发光性能的影响

采用高温固相法按化学式Zn_xMg_(1-x)Ga₂O₄∶Cr3+(x=0,0.2,0.6,0.8,1.0)配比原料制备了一系列红色长余辉发光材料。X射线衍射(XRD)分析表明样品物相均为面心立方结构。光致发光特性表明样品的红光发射峰均由以Cr3+为发光中心的电子2E—4A₂跃迁所致,Cr3+的激发带与基质发射带之间有大面积重叠,两者间存在有效的能量传递。余辉衰减曲线与热释光谱分析表明,不同Zn掺入量的样品余辉衰减快慢不同,是由于其中存在的陷阱能级深度不同,且陷阱能级越深,其余辉时间越长。     

(Zn_(1-x),Mg_x)_2GeO_4∶Mn~(2+)的荧光以及长余辉发光性能

采用高温固相法制备了一系列(Zn_(1-x),Mg_x)_2GeO_4∶Mn~(2+)(0≤x≤0.25)绿色荧光粉,并研究了Mg离子对(Zn_(1-x),Mg_x)_2GeO_4∶Mn~(2+)的结构、荧光以及长余辉发光性能的影响。Mg离子取代Zn进入Zn_2GeO_4晶格,形成(Zn_(1-x),Mg_x)_2GeO_4固溶体,并产生了晶格畸变。光谱分析结果表明,样品中位于533 nm的绿色荧光源于Mn~(2+)的~4T_1(~4G)→~6A_1(~6S)跃迁。随着Mg离子浓度的增加,(Zn_(1-x),Mg_x)_2GeO_4∶Mn~(2+)样品的激发光谱出现了蓝移现象,说明Mg离子进入到Zn_2GeO_4晶格中对其晶格结构产生了影响,导致(Zn_(1-x),Mg_x)_2GeO_4的带宽发生改变。发射光谱则表明Mg离子进入Zn_2GeO_4晶格引起Mn~(2+)的~4T_1(~4G)→~6A_1(~6S)跃迁绿色荧光发光强度的增强。Zn_2GeO_4基质中的氧空位缺陷陷阱深度由于基质带宽的变化而变深,样品具有良好的长余辉发光效果。通过热释光谱分析研究了材料中缺陷陷阱的特征,进一步证实了(Zn_(1-x),Mg_x)_2GeO_4中缺陷陷阱深度发生改变。根据光谱分析结果给出了(Zn_(1-x),Mg_x)_2GeO_4∶Mn~(2+)中荧光与余辉发光的产生机理。     

白宝石衬底上生长的MgxZn1-xO晶体薄膜的结构和光学性能

在白宝石 (sapphire)衬底上低温外延生长出了MgxZn1 -xO晶体薄膜 .x射线衍射 (XRD)及能量色散x射线 (EDX)分析表明 ,MgxZn1 -xO薄膜的晶体结构依赖于薄膜中Mg的组分x,随着Mg组分的增大 ,MgxZn1 -xO薄膜的结构从与ZnO晶体一致的六方结构转变为与MgO晶体一致的立方结构 .对MgxZn1 -xO薄膜的紫外透射光谱及紫外光致荧光谱 (UVPL)的分析表明 ,随着Mg组分的增大 ,光学吸收边产生明显的蓝移 ,表明MgxZn1 -xO晶体薄膜的带隙增大 ,且带隙连续可调 .吸收光谱和XRD测量显示 ,带隙高达 5 6 5eV的MgxZn1 -xO晶体薄膜与MgO之间的晶格失配仅为0 16 % .     

GaN1-xPx三元合金的光学与结构特性

对采用金属有机化学气相淀积(MOCVD)技术生长的GaN1-xPx三元合金进行了低温光致发光(PL)和X射线衍射(XRD)测试分析,与来自GaN层的带边发射相比,P的摩尔分数比为0．03,0．11和0．15的GaN1-xPx的光致发光峰分别呈现出了73meV,78meV和100meV的红移,文中将这种红移归因于GaN1-xPx合金具有大的带隙能量弯曲系数。X射线衍射结果表明GaN1-xPx三元合金仍为六方结构晶体,且随着P组份比的增加,GaN1-xPx合金的(0002)衍射峰逐渐向小角度方向移动,即晶格常量变大,同时,(0002)衍射峰谱线不断宽化,说明由于替位式P原子的不规则分布以及部分间隙P原子的影响造成了GaN1-xPx样品的晶格畸变。在GaN1-xPx的光致发光谱及X射线衍射谱中均未观测到相应的有关GaP的峰,表明所生长的高P含量的GaN1-xPx三元合金没有产生明显的相分离。     

铽掺钇配合物[(TbxY1-x)(HL)L'Cl·1/2H2O]的合成及荧光性质研究

以1,3,5-苯三甲酸根(BTC3-)为阴离子配体,1,10邻菲啰啉(phen)为中性配体,以不同摩尔比铽、钇离子为中心体,合成了系列铽掺钇配合物.经C,N,H元素分析,稀土总量络合滴定和铽、钇分量的测定推测配合物的组成为(TbxY1-x)(HL)L'C1·1/2H2O(x=0.10,0.30,0.50,0.70,0....     

LED用荧光粉Sr（S1-xSex）：Eu^2＋的合成和光谱性质研究

采用高温固相法合成了Sr(S1-xSex)系列硫属化合物掺Eu2 荧光粉.XRD表明荧光粉的组成为单相,而且体系Sr(Sl-xSex):0.005Eu2 中晶胞参数随着组成的变化呈现良好的线性关系,遵守韦加定律.漫反射光谱与激发光谱吻合,说明荧光粉吸收的能量能够有效地激发发光中心而发光,激发光谱中较低能量区域覆盖了400～500 nm的光谱范围,与蓝光LED芯片的发射光匹配.发射光谱呈现的是Eu2 离子的5d→4f特征跃迁发射带,当x由0增加到1.0的过程中,发射峰值波长由617 nm逐渐蓝移到571 nm.不同基质中掺杂的Eu2 离子的荧光寿命均为微秒数量级,与Eu2 离子的4f65d1→4f7跃迁相符合.将荧光粉封装在发蓝色光(λ=460 nm)的GaN芯片上制作了LED器件,测量了器件的发光强度、色纯度和色坐标等参数.Sr(S1-xSex):Eu2 系列硫属化合物掺铕荧光粉能够有效地被GaN芯片发出的蓝色光激发,发出从橙色到红色的可见光,是一类较好的LED用荧光粉.     

Cs3Cu2I5晶体薄膜吸收谱的研究

本文测定了Ｃｓ３Ｃｕ２ Ｉ５ 晶体薄膜在室温及液氮温度下的吸收谱,并依此计算出该材料的激子参数,即激子束缚能ΔＥ（１）ｅｘ ＝ （０．５３±０．０７）ｅＶ,激子半径ａｅｘ ＝ ０．３２６ ｎｍ ,禁带宽度Ｅｇ ＝ （５．００±０．０７）ｅＶ。在谱分析的基础上,论证了Ｃｓ３Ｃｕ２Ｉ５ 的电子和激子激发定域在该晶体的ＣｕＩ亚晶格之中,同时,揭示了在低温下Ｃｓｘ Ｃｕ１－ ｘ Ｉ系列化合物的第一激子峰位置随其摩尔组分变化的规律。     

Band gap and electronic structure of an epitaxial, semiconducting Cr0.80Al0.20 thin film

Cr(1-x)Al(x) exhibits semiconducting behavior for x = 0.15-0.26. This Letter uses hard x-ray photoemission spectroscopy and density functional theory to further understand the semiconducting behavior. Photoemission measurements of an epitaxial Cr(0.80)Al(0.20) thin film show several features in the valence band region, including a gap at the Fermi energy (E(F)) for which the valence band edge is 95 ± 14 meV below E(F). Theory agrees well with the valence band measurements, and shows an incomplete gap at E(F) due to the hole band at M shifting almost below E(F).